Dog biting - dog on dog

Question
We have three adult female dogs - all adopted terrier-mixes.  Our oldest, Chiclet, a 10-year-old Jack Russell Terrier Mix has attacked our smallest, Zippy, a Chihuahua/Yorkie mix, about six times over the past two years over what appear to be jealousy and pack order issues.  Five weeks ago, we had the worst incident yet, and Zippy required 15 stitches as a result.  Normally, the dogs are absolutely fine together, but there are no visible signs of aggression immediately prior to these attacks, so they are hard to predict.  We had been advised by professionals to now keep them apart at ALL times; we integrated them two weeks after the attack, and there have been no further problems.  Are we sitting on a ticking time bomb?  We have tried to re-home Chiclet unsuccessfully, so our only other option is euthanasia.  How can we euthanize a sweet dog, who is ONLY dangerous to one other dog and not other dogs or humans?  Also, we have two young boys, so it is not feasible to our lifestyle to keep our 3 dogs separated on a long-term basis.  Thanks for any input.

Answer
If you haven't addressed the underlying reason for the behavior, then yes, you are most likely "sitting on a ticking time bomb".

I see some possible options to euthanasia.  

1. Completely exhaust all resources for re-homing Chiclet including newspaper ads, vet clinics, local humane societies, JRT breed rescues.

2. Consider re-homing one or both of the other dogs.

3. Have your vet examine Chiclet to be sure there is no medical reason for her aggression.

4. Hire a professional to develop a protocol for management and behavior modification that is workable for your family. If you need help finding someone in your area, check member directories at IAABC.org APDT.com NADOI.org.  Your veterinarian can refer you to a vet behaviorist.

Aggression between housemates can be very challenging.  If your lifestyle prevents you from safely managing the behavior by keeping Chiclet separated - crated, gated and/or leashed and directly supervised - around Zippy (and vice versa), will you be able to implement plans for behavior modification?  Only you can determine if your family has the time and determination to devote to the dog.